Wrapper comprising metal particles

ABSTRACT

A wrapper according to an aspect includes a pulp layer and metal particles uniformly distributed inside the pulp layer, wherein the metal particles contain a metal flake paste.

TECHNICAL FIELD

The present disclosure relates to a wrapper comprising metal particles. More specifically, the present disclosure relates to a wrapper in which metal particles are uniformly distributed in a pulp layer.

BACKGROUND ART

Recently, the demand for alternative methods to overcome the shortcomings of general cigarettes has increased. For example, there is an increasing demand for a method of generating aerosols by heating an aerosol generating material in cigarettes, rather than by burning cigarettes. Accordingly, studies on a heating-type cigarette or a heating-type aerosol generating device have been actively conducted.

DESCRIPTION OF EMBODIMENTS Technical Problem

The present disclosure provides a wrapper comprising metal particles. A technical problem to be solved is not limited to the technical problem described above, and other technical problems may exist.

Technical Solution to Problem

A wrapper according to an aspect includes a pulp layer; and metal particles uniformly distributed inside the pulp layer, and the metal particles contain a metal flake paste.

Advantageous Effects of Disclosure

In a heating type cigarette, thermal conductivity of a wrapper wrapping at least a part of the cigarette may be increased. Accordingly, a temperature of a tobacco rod is maintained during smoking through uniform heat transfer, and uniform tobacco taste may be obtained. In addition, it is possible to obtain an effect in which, as hot air supplied by a heater comes into contact with air introduced through a periphery of a tobacco rod, forced convective heat transfer of the tobacco rod is minimized or removed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example in which a cigarette is inserted into a holder.

FIG. 2 is a configuration diagram illustrating an example of a cigarette.

FIG. 3 is a diagram illustrating an example of a wrapper containing a metal flake paste.

BEST MODE

A wrapper according to an aspect includes a pulp layer; and metal particles uniformly distributed inside the pulp layer, wherein the metal particles contain a metal flake paste.

In the wrapper described above, the metal flake paste may be made of aluminum, steel, iron, copper or a metal alloy.

In the wrapper described above, the metal flake paste may be made by a method including a first process of flaking raw material aluminum powder in an organic solvent containing aromatic hydrocarbons as a main component to obtain aluminum flakes; and a second process of treating the aluminum flakes obtained in the first process with an organic compound having a polar group and forming a paste.

In the wrapper described above, the organic compound having the polar group may be at least one selected from the group consisting of fatty acids, aliphatic amines, fatty acid amides, aliphatic alcohols, and esters composed of the fatty acids and the aliphatic alcohols.

A cigarette according to another aspect includes a tobacco rod containing an aerosol generating material; at least one filter segment; and a wrapper that wraps at least one of the tobacco rod and the at least one filter segment, wherein the wrapper includes a pulp layer, and at least one metal particle distributed inside the pulp layer, and the metal particle contains a metal flake paste.

In the cigarette described above, the metal flake paste may be made of aluminum, steel, iron, copper or a metal alloy.

In the cigarette described above, an aerosol may be generated from the tobacco rod by an electric-heating-type heater inserted into the cigarette.

A method of manufacturing metal flake paste according to another aspect includes a first process of flaking raw material aluminum powder in an organic solvent containing aromatic hydrocarbons as a main component to obtain aluminum flakes; and a second process of treating the aluminum flakes obtained in the first process with an organic compound having a polar group and forming a paste.

In the method described above, the organic compound having the polar group may be at least one selected from the group consisting of fatty acids, aliphatic amines, fatty acid amides, aliphatic alcohols, and esters composed of the fatty acids and the aliphatic alcohols.

MODE OF DISCLOSURE

With respect to the terms in the various embodiments, the general terms which are currently and widely used are selected in consideration of functions of structural elements in the various embodiments of the present disclosure. However, meanings of the terms can be changed according to intention, a judicial precedence, the appearance of a new technology, and the like. In addition, in certain cases, a term which is not commonly used can be selected. In such a case, the meaning of the term will be described in detail at the corresponding portion in the description of the present disclosure. Therefore, the terms used in the various embodiments of the present disclosure should be defined based on the meanings of the terms and the descriptions provided herein.

In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

Hereinafter, the present disclosure will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the present disclosure are shown such that one of ordinary skill in the art may easily work the present disclosure. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating an example in which a cigarette is inserted into a holder.

Referring to FIG. 1, a cigarette 2 may be inserted into a holder 1. When the cigarette 2 is inserted, a heater 130 is inside the cigarette 2. Accordingly, an aerosol generating material of the cigarette 2 is heated by the heated heater 130 to generate an aerosol.

The cigarette 2 may have a shape similar to a general combustion type cigarette. For example, the cigarette 2 may be divided into a first portion 210 containing an aerosol generating material and a second portion 220 including a filter and so on.

The entire first portion 210 may be inserted into the holder 1 and the second portion 220 may be exposed to the outside. Alternatively, only part of the first portion 210 may be inserted into the holder 1, or part of the first portion 210 and the second portion 220 may be inserted thereinto.

A user may inhale an aerosol with the second portion 220 in the mouth. In this case, an aerosol is generated when external air passes through the first portion 210, and the generated aerosol passes through the second portion 220 to be delivered to user's mouth.

External air may be introduced through at least one air passage formed in the holder 1. Alternatively, external air may be introduced through at least one hole formed in a surface of the cigarette 2.

FIG. 2 is a configuration diagram illustrating an example of a cigarette.

Referring to FIG. 2, the cigarette 2 includes a tobacco rod 210, a first filter segment 221, a cooling structure 222, and a second filter segment 223. The first portion described above with reference to FIG. 1 includes the tobacco rod 210, and the second portion includes the first filter segment 221, the cooling structure 222, and the second filter segment 223.

Referring to FIG. 2, the cigarette 2 may be wrapped by wrappers 231, 232, 233, 234, 235, and 236. For example, the tobacco rod 210 is wrapped by the first wrapper 231, and the first filter segment 221 is wrapped by the second wrapper 232. Further, the cooling structure 222 is wrapped by the third wrapper 233, and the second filter segment 223 is wrapped by the fourth wrapper 234.

The fifth wrapper 235 may surround outer edges of the first wrapper 231, the second wrapper 232, and the third wrapper 233. In other words, the tobacco rod 210, the first filter segment 221, and the cooling structure 222 of the cigarette 2 may be further wrapped by the fifth wrapper 235. In addition, the sixth wrapper 236 may surround at least a part of the fifth wrapper 235 and an outer edge of the fourth wrapper 234. In other words, at least a part of the cooling structure 222 of the cigarette 2 and the second filter segment 223 may be further wrapped by the sixth wrapper 236.

The first wrapper 231, the second wrapper 232, the fifth wrapper 235, and the sixth wrapper 236 may be made of a general wrapping paper. For example, the first wrapper 231, the second wrapper 232, the fifth wrapper 235, and the sixth wrapper 236 may be porous wrapping paper or non-porous wrapping paper. For example, a thickness of the first wrapper 231 may be approximately 61 μm, porosity thereof may be approximately 15 CU, a thickness of the second wrapper 232 may be approximately 63 μm, and porosity thereof may be approximately 15 CU, and are not limited thereto. In addition, a thickness of the fifth wrapper 236 may be approximately 66 μm, porosity thereof may be approximately 10 CU, a thickness of the sixth wrapper 236 may be 66 μm, and porosity thereof may be approximately 17 CU, and are not limited thereto.

In addition, aluminum foil may be further included on an inner surface of the first wrapper 231 and/or an inner surface of the second wrapper 232.

The third wrapper 233 and the fourth wrapper 234 may be made of hard wrapping paper. For example, a thickness of the third wrapper 233 may be approximately 158 μm, porosity thereof may be approximately 33 CU, a thickness of the fourth wrapper 234 may be approximately 155 μm, and porosity thereof may be approximately 46 CU, and are not limited thereto.

A predetermined material may be added to the fifth wrapper 235 and the sixth wrapper 236. Here, for example, the predetermined material may include silicon and is not limited thereto. For example, silicon has properties such as heat resistance with little change in temperature, oxidation resistance for preventing oxidization, resistance to various chemicals, water repellency to water, or electrical insulation. However, the fifth wrapper 235 and the sixth wrapper 236 may be coated with any material having the above-described properties without limitation even if the material is not silicon.

The fifth wrapper 235 and the sixth wrapper 236 may prevent the cigarette 2 from being burned. For example, when the tobacco rod 210 is heated by the heater 130, the cigarette 2 may be burned. Specifically, when a temperature increases above an ignition point of any one of materials included in the tobacco rod 210, the cigarette 2 may be burned. Even in this case, the cigarette 2 may be prevented from being burned because the fifth wrapper 235 and the sixth wrapper 236 contain a non-combustible material.

In addition, the fifth wrapper 235 may prevent the holder 1 from being contaminated by materials generated in the cigarette 2. Liquid materials may be generated in the cigarette 2 by user's puff. For example, as an aerosol generated in the cigarette 2 is cooled by external air, liquid materials (for example, moisture, etc.) may be generated. As the fifth wrapper 235 wraps the cigarette rod 210 and/or the first filter segment 221, a liquid material generated in the cigarette 2 may be prevented from leaking out of the cigarette 2. Accordingly, an inside of the holder 1 may be prevented from being contaminated by the liquid material generated in the cigarette 2.

A diameter of the cigarette 2 may be within a range of 5 mm to 9 mm, and a length thereof may be approximately 48 mm, which are not limited thereto. For example, a length of the tobacco rod 210 may be approximately 12 mm, a length of the first filter segment 221 may be approximately 10 mm, a length of the cooling structure 222 may be approximately 14 mm, and a length of the second filter segment 223 may be approximately 12 mm, which are not limited thereto.

A structure of the cigarette 2 illustrated in FIG. 2 is only an example, and some configurations may be omitted. For example, the cigarette 2 may not include one or more of the first filter segment 221, the cooling structure 222, and the second filter segment 223.

The tobacco rod 210 contains an aerosol generating material. For example, the aerosol generating material may include at least one of glycerin, propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and oleyl alcohol.

In addition, the tobacco rod 210 may contain other additives such as flavoring agent, wetting agent, and/or organic acid. For example, the flavoring agent includes licorice, sucrose, fructose syrup, isosweet, cocoa, lavender, cinnamon, cardamom, celery, fenugreek, cascarilla, sandalwood, bergamot, geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, mint oil, cassia bark, caraway, cognac, jasmine, chamomile, menthol, ylang-ylang, salvia, spearmint, ginger, cilantro, coffee, or so on. In addition, the wetting agent may include glycerin, propylene glycol or so on.

As an example, the tobacco rod 210 may be filled with a reconstituent tobacco sheet.

As another example, the tobacco rod 210 may be filled with cut tobacco. Here, cut tobacco may be made by finely cutting a plate leaf sheet.

As another example, the tobacco rod 310 may be filled with a plurality of tobacco strands made by shredding the plate leaf sheet. For example, the tobacco rod 310 may be formed by combining a plurality of tobacco strands in the same direction (parallel) or randomly.

For example, the plate leaf sheet may be made by the following process. First, a tobacco raw material is pulverized to make a slurry in which an aerosol material (for example, glycerin, propylene glycol, or so on), a flavoring liquid, binder (for example, guar gum, xanthan gum, carboxymethyl cellulose (CMC), or so on), water, and so on are mixed, and then a plate leaf sheet is formed by using the slurry. When making the slurry, natural pulp or cellulose may be added, and one or more binders may be mixed and used. Meanwhile, tobacco strands may be made by cutting or shredding the dried plate leaf sheet.

The tobacco raw material may be tobacco leaf pieces, tobacco stems, and/or tobacco fines made during tobacco treatment. In addition, other additives such as wood cellulose fibers may be contained in the plate leaf sheet.

5% to 40% of an aerosol generating material may be added to the slurry, and 2% to 35% of the aerosol generating material may remain in the plate leaf sheet. Preferably, 5% to 30% of an aerosol generating material may remain in the plate leaf sheet.

In addition, before a process in which the tobacco rod 210 is wrapped by the first wrapper 231, a flavoring liquid such as menthol or moisturizer may be sprayed to the center of the tobacco rod 210 to be added.

The first filter segment 221 may be a cellulose acetate filter. For example, the first filter segment 221 may have a tube-shaped structure having a hollow formed therein. The first filter segment 221 may have an appropriate length within a range of 4 mm to 30 mm and is not limited thereto. Preferably, the length of the first filter segment 221 may be 10 mm and is not limited thereto.

A diameter of the hollow formed in the first filter segment 221 may be appropriately selected within a range of 2 mm to 4.5 mm and is not limited thereto.

When the first filter segment 221 is made, hardness of the first filter segment 221 may be adjusted by adjusting the content of plasticizer.

In addition, the first filter segment 221 may be made by inserting a structure such as a film or a tube formed of the same material or different materials into the interior (for example, a hollow).

The first filter segment 221 may be made by using cellulose acetate. Accordingly, when the heater 130 is inserted, a phenomenon in which an internal material of the tobacco rod 210 is pushed back may also be prevented, and a cooling effect of an aerosol may be obtained.

The cooling structure 222 cools an aerosol generated when the heater 130 heats the tobacco rod 210. Accordingly, a user may inhale the aerosol cooled to an appropriate temperature.

A length or a diameter of the cooling structure 222 may be variously determined according to a shape of the cigarette 2. For example, the length of the cooling structure 222 may be appropriately selected within a range of 7 mm to 20 mm. Preferably, the length of the cooling structure 222 may be approximately 14 mm and is not limited thereto.

The cooling structure 222 may be made by weaving polymer fibers. In this case, fibers made of polymer may be coated with a flavoring liquid. Alternatively, the cooling structure 222 may be formed by weaving both a separate fiber coated with the flavoring liquid and a fiber made of polymer.

Alternatively, the cooling structure 222 may be formed by a crimped polymer sheet. The polymer is made of a material selected from a group composed of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), and aluminum foil.

As the cooling structure 222 is formed by a woven polymer fiber or a crimped polymer sheet, the cooling structure 222 may include a single channel or a plurality of channels extending in a longitudinal direction. Here, the channel means a passage through which gas (for example, air or aerosol) passes.

For example, the cooling structure 222 formed of a crimped polymer sheet may be formed of a material having a thickness between approximately 5 μm and approximately 500 μm, for example between approximately 10 μm and approximately 250 μm. In addition, the total surface area of the cooling structure 222 may be between approximately 300 mm²/mm and approximately 1000 mm²/mm. In addition, a specific surface area of an aerosol cooling element may be formed of a material between approximately 10 mm²/mg and approximately 100 mm²/mg.

Meanwhile, the cooling structure 222 may include a thread containing a volatile flavor component. Here, the volatile flavor component may be menthol and is not limited thereto. For example, the thread may be filled with the sufficient amount of menthol to provide 1.5 mg or more of menthol to the cooling structure 222.

The second filter segment 223 may be a cellulose acetate filter. A length of the second filter segment 223 may be appropriately selected within a range of 4 mm to 20 mm. For example, the length of the second filter segment 223 may be approximately 12 mm and is not limited thereto.

While forming the second filter segment 223, the second filter segment 223 may also be formed to generate flavor by spraying a flavoring liquid onto the second filter segment 223. Alternatively, separate fiber coated with the flavoring liquid may also be inserted into the second filter segment 223. An aerosol generated in the tobacco rod 210 is cooled by passing through the cooling structure 222, and the cooled aerosol is delivered to a user through the second filter segment 223. Accordingly, when a flavor element is added to the second filter segment 223, an effect of enhancing persistence of flavor delivered to the user may be obtained.

Aluminum foil may also be further included on an inner surface of any one of the first wrapper 231 to the sixth wrapper 236. Alternatively, paper may be further included or a non-combustible material may be applied to the inner surface of any one of the first wrapper 231 to the sixth wrapper 236. In this case, it may be difficult to ignite the cigarette 2 due to the characteristics (that is, non-combustible properties) of aluminum foil, paper, or non-combustible material. In addition, in order to further apply aluminum foil, paper, or non-flammable material to any one of the first wrapper 231 to the sixth wrapper 236, additional equipment needs to be used, and thereby, manufacturing cost of the wrappers may increase. In addition, when the aluminum foil applied to the wrapper is damaged due to various reasons, quality difference between the wrappers, such as a decrease in thermal efficiency, may be generated.

In the wrapper according to an embodiment, a metal flake paste may be uniformly distributed in a pulp layer by dispersing the metal flake paste in the pulp layer of a wrapper during a manufacturing process of the wrapper. Accordingly, a phenomenon that a metal layer is damaged in a wrapper including a pulp layer and a metal layer divided from each other or a phenomenon that the metal layer is detached (separated) from the pulp layer may be prevented from occurring. Accordingly, a heat conduction efficiency of the wrapper may be increased. Hereinafter, an example of a wrapper to which a metal flake paste is applied will be described with reference to FIG. 3.

FIG. 3 is a diagram illustrating an example of a wrapper including a metal flake paste.

Wrappers 300, 301, and 302 illustrated in FIG. 3 may be some of the first to sixth wrappers 231 to 236 of FIG. 2.

Referring to FIG. 3A, the wrapper 301 includes a metal layer 310 and a pulp layer 320, and the metal layer 310 and the pulp layer 320 are different from each other. Accordingly, in the wrapper 301 of FIG. 3A, the metal layer 310 may be damaged or the metal layer 310 may be separated from the pulp layer 320.

Referring to FIG. 3B, the wrapper 302 contains a plurality of metal particles 330 distributed in the pulp layer 340. Here, the pulp layer 320 of FIG. 3A and the pulp layer 340 of FIG. 3B are the same. In addition, the metal particles 330 of FIG. 3B means the metal flake paste described above with reference to FIG. 2.

The metal particles 330 (that is, the metal flake paste) of the wrapper 302 are uniformly distributed inside the pulp layer 340. For example, the metal particles 330 may be applied by mixing and spraying a pulp raw material and the metal particles 330 during a manufacturing process of base paper, or by impregnating and spraying the metal particles 330 during the manufacturing process. Accordingly, a wrapper having excellent thermal conductivity may be manufactured. Here, a method of manufacturing the base paper is obvious to those skilled in the art, and thus, detailed description thereof will be omitted. In order to enable the metal particles 330 to be densely dispersed during the mixing process described above, a method such as high-speed stirring or ultrasonic stirring (homomixer) may be used. In addition, thermal conductivity of the wrapper 302 may be increased by adjusting concentration of the metal particles 330.

For example, reflectivity of the wrapper 302 may be 65 to 95%, and average emissivity thereof may be 0.25 to 0.0005 ε, and are not limited thereto.

Hereinafter, a manufacturing process of the metal particles 330 (that is, a metal flake paste) will be described.

The manufacturing process of the metal flake paste includes a first process of obtaining metal flakes by flaking metal powder in an organic solvent containing aromatic hydrocarbons, and a second process of treating the metal flakes obtained in the first process with an organic compound having a polar group and forming into a paste.

Here, a metal flake paste may be formed of aluminum, steel, iron, copper, a metal alloy, or so on, and a raw material of the metal flake paste is not limited to the material described above. For the sake of convenient description, the metal flake paste will be hereinafter described as being an aluminum flake paste. However, a manufacturing process of an aluminum flake paste to be described below may be replaced with a manufacturing process of another metal flake paste.

The first process is a process of obtaining aluminum flakes by flaking raw material aluminum powder in an organic solvent containing aromatic hydrocarbons as a main component. Hereinafter, a raw material used in the first process, conditions of the first process, and so on will be described.

A grinding device having a grinding medium is used to flake the raw aluminum powder. Here, “flaking” means that the particulate powder is molded into a flake shape (scale shape) by using the grinding device and so on. A type of the grinding device used in the present disclosure is not limited in particular, and a known grinding device may be appropriately used. For example, an attritor type grinding device having a rotating arm therein, or a cylindrical ball mill may be preferably used. Among the above-described grinding devices, the cylindrical ball mill is preferably used in particular because aluminum flakes of higher luminance may be obtained thereby.

In addition, in the manufacturing method of the present disclosure, when a ball mill is used, a rotation speed of the ball mill is preferably set to 95% or less of a critical rotation speed. The critical rotation speed refers to a rotation speed at which a ball (grinding media) is fixed to an inner wall of the ball mill by centrifugal force when the 0rotation speed is increased more than the critical rotation speed, and is represented by following Equation 1.

n=[1/(2π)]×(g/r)1/2   [Equation 1]

In Equation 1 described above, n is a rotation speed (rpm), g is acceleration of gravity (3528000 cm/min²), and r is a ball mill radius (cm).

When the rotation speed of the ball mill exceeds 95% of the critical rotation speed, a pulverization effect becomes stronger than a grinding effect, and thus, sufficient flaking may not be made, and in contrast to this, large flake particles are divided to generate fine particles, and thus, luminance of a coating film containing the aluminum flake paste tends to decrease. In addition, in a case in which steel ball grinding media with a diameter of 1 mm or less are used in particular, when a rotation speed of a ball mill approaches the critical rotation speed, impact force due to collision between the grinding media increases, and thus, life of the grinding media is reduced to suppress a consecutive use. The reason is that, in general, a hardening treatment film is not formed on the surface of the grinding media of steel balls having a diameter of 1 mm or less. The life of the grinding media may be extended by keeping a rotation speed of the ball mill at 95% or less of the critical rotation speed.

A grinding time is not limited in particular and may be appropriately determined according to a diameter of the grinding media, mass of the grinding media, the amount of a grinding solvent, the number of rotations, and so on. Usually, the grinding time is between 3 to 48 hours.

The grinding media is not limited in particular, and various materials such as steel balls, stainless balls, glass balls, or ceramic balls may be used therefor, but from the viewpoint of specific gravity and economy, a spherical media made of a material containing steel is preferably used.

In addition, the grinding media to be used is preferably spherical and need not necessarily be true spherical grinding media, and substantially spherical grinding media may be used therefor. In addition, a size of the grinding media may be appropriately selected depending on the aluminum flakes to be finally obtained, and, for example, a diameter thereof is preferably in a range of 0.3 mm to 5.0 mm. In addition, two or more types of the grinding media different in diameter may be mixed and used as the grinding medium. In addition, a grinding medium having a diameter exceeding 1.0 mm may be included in the grinding device used in the present disclosure. As will be described below, the amount of the grinding media may be changed depending on the amount of raw material powder (for example, aluminum powder) to be introduced into the grinding device.

For example, the raw material aluminum powder used as a raw material of the aluminum flake paste is not limited in particular, and composition thereof may be composed of only aluminum or may be composed of an aluminum-based alloy, and purity of aluminum is not limited in particular. In order to further increase gloss of a coating film and a printed matter, pure aluminum is preferably used in general, and aluminum having purity of 99.9 mass % or more is used more preferably.

In the first process, raw material aluminum powder is flaked to obtain aluminum flakes, and then a solid liquid separation operation such as a filtration operation or a screen operation may be performed to extract the aluminum flakes. For example, after flaking (grinding) is made, an operation may be performed in which a slurry containing aluminum flakes in a ball mill is washed with mineral spirit and placed on a vibration screen, and a solid-liquid separation of the passed slurry is made with a fan filter, and aluminum flakes (as a filter cake) is obtained. Here, the “filter cake” refers to a semi-solid material remaining after an organic solvent containing aromatic hydrocarbons is removed. In performing the filtration operation or the screen operation, the grinding media may be removed from the organic solvent containing the aromatic hydrocarbons.

In addition, the filtration operation or the screen operation is not limited to first process and may also be performed suitably in each process to be described below.

In the first process, after raw material aluminum powder is flaked to obtain aluminum flakes, an organic solvent containing aromatic hydrocarbons as a main component may be changed to another solvent by solvent replacement or solvent addition. In this case, the organic solvent containing the aromatic hydrocarbons as the main component may be changed to a solvent having solubility lower than solubility of “an organic compound having a polar group” to be described below. Accordingly, in the second process to be described below, dissolution of the organic compound having the polar group for the solvent may be suppressed more than before. As will be described below, the organic compound having the polar group has an effect of increasing storage stability of the aluminum flake paste in any case in which the organic compound adheres to a surface of aluminum flakes and is contained in a solvent, but it is more preferable that the organic compound adheres to surfaces of the aluminum flakes in increasing the storage stability. Accordingly, by changing the solvent, dissolution of the organic compound having the polar group in the solvent may be suppressed, and the amount of adhesion to the surfaces of the aluminum flakes may be increased, and thus, an effect of protecting the surfaces of the aluminum flakes may be enhanced.

The second process is a process of treating the aluminum flakes obtained in the first process with an organic compound having a polar group and forming a paste. Here, “treating with an organic compound having a polar group” is a process of which a purpose is to cause the organic compound having the polar group to adhere to surfaces of aluminum flakes. In addition, when the second process is performed in a state in which a pasted solvent is added to the aluminum flakes, the organic compound having the polar group adheres to the surfaces of the aluminum flakes and may be contained in the pasted solvent. Hereinafter, a raw material and conditions used in the second process will be described.

In the second process, an operation of treating the aluminum flakes obtained in the first process with an organic compound having a polar group is performed.

When an organic solvent containing aromatic hydrocarbons as a main component is used as a grinding solvent, solubility for fatty acids such as oleic acids and stearic acids is increased more than when aliphatic hydrocarbons (representatively, mineral spirit) is used as the grinding solvent. The fatty acids such as oleic acid and stearic acid are added as grinding aids during flaking (grinding) and adhere to surfaces of aluminum flakes after being flaked, thereby, performing provision of parallel alignment of the aluminum flakes, suppression of aggregation, protection of the surfaces of the aluminum flakes, and so on. However, when solubility for the grinding solvent is increased, the amount of fatty acids adhering to the surfaces of the aluminum flakes is reduced as a result. Accordingly, aggregation and so on occurs over time, and storage stability of an aluminum flake paste is decreased. However, in a manufacturing method of the present disclosure, the storage stability of the aluminum flake paste may be enhanced by treating the aluminum flakes obtained in the first process with an organic compound having a polar group.

That is, the manufacturing method of the present disclosure may obtain an excellent effect in which an aluminum flake paste having good storage stability is obtained. This is because aggregation of the aluminum flakes in the aluminum flake paste is suppressed by treating the aluminum flakes with the organic compound having the polar group.

As described above, even when an organic compound having a polar group adheres to surfaces of aluminum flakes or is contained in a pasting solvent, an effect of enhancing storage stability is obtained. However, in order to enhance the storage stability, it is more preferable that the organic compound having the polar group adheres to the surfaces of the aluminum flakes.

The organic compound having the polar group used in the manufacturing method of the present disclosure is an organic compound having a polar group, such as hydroxyl group, carboxyl group, amino group, amide group (amide bond), or ester group (ester bond), and a chemical structure thereof is not limited in particular. At least one organic compound selected from a group consisting of fatty acids, aliphatic amines, fatty acid amides, aliphatic alcohols, and esters composed of the fatty acids and the fatty alcohols may preferably be used. An organic compound having a polar group may be the same as or different from a compound added as a grinding aid in the first process.

The fatty acids may include, for example, caprylic acids, capric acids, lauric acids, myristic acids, oleic acids, stearic acids, linoleic acids, arachidonic acids, behenic acids, and so on. In addition, the aliphatic amines may include, for example, laurylamine, miristeelamine, palmitylamine, and stearylamine. In addition, the fatty acid amides may include, for example, lauric acid amides, palmitic acid amides, oleic acid amides, stearic acid amides, behenic acid amides, and so on. In addition, the aliphatic alcohols may include, for example, capryl alcohols, lauryl alcohols, miristeel alcohols, oleyl alcohols, stearyl alcohols, behenyl alcohols, and so on. In addition, the esters composed of the fatty acids and the aliphatic alcohols may include, for example, lauric acid methyl, oleic acid methyl, stearic acid methyl, stearic acid octyl, myristic acid isopropyl, stearic acid butyl, palmitic acid octyl, oleic acid octyl, palmitic acid propyl, and so on.

In the second process, ‘pasting” means that viscosity of a slurry containing aluminum flakes is increased in the first process (when the aluminum flakes are obtained as a filter cake, the aluminum flakes become a highly viscous fluid). This operation is usually performed by adding a pasted solvent, but when viscosity of a mixing system is higher when an organic compound having a polar group is added to aluminum flakes, a solvent constituting the mixing system is used as a pasted solvent, and thus, it is not necessary to add a separate pasted solvent. When the organic compound having the polar group is added to the aluminum flakes, in a case in which the viscosity of the mixing system is lower, it is also possible to increase the viscosity of the mixing system by adding a pasted solvent to the mixing system or by replacing a solvent constituting the mixing system with the pasted solvent.

Here, the “pasted solvent” refers to a compound mixed with aluminum flakes to form a paste. An organic solvent containing aromatic hydrocarbons as a main component in the first process may be used as the pasted solvent, or when the second process includes a solvent, the solvent may be used as the pasted solvent, and another solvent may be used as the pasted solvent by adding the solvent or by replacing the solvent as described above. A material of the pasted solvent is not limited in particular, and in addition to an organic solvent containing aliphatic hydrocarbons (for example, mineral spirits) and aromatic hydrocarbons as a main component, a glycol ether solvent and so on may be used as the material of the pasted solvent. In addition, the content of the pasted solvent in the aluminum flake paste is not limited in particular, and when the content is in a range of 15 mass % or more and 50 mass % or less, storage stability may be further increased, and dispersibility of the aluminum flakes may be increased in a coating material at the time of coating. It is more preferable that the content is in a range of 25 mass % or more and 40 mass % or less.

Furthermore, in addition to the first and second processes described above, a process of adding an antioxidant may be further included. Among grinding aids such as fatty acids adhering to surfaces of aluminum flakes or organic compounds having polar groups, a material having an unsaturated double bond in a structure thereof may have a property (deterioration) that causes a radical reaction to denature or polymerize. Due to this deterioration, the aluminum flakes aggregate to each other or a parallel arrangement of the aluminum flakes is adversely affected to decrease luminance.

the deterioration may be stopped or suppressed by adding an antioxidant. A step of a manufacturing process in which an operation of adding the antioxidant is performed may be appropriately determined according to types of a grinding aid added to aluminum flakes and an organic compound having a polar group. Specifically, when a material, which has an unsaturated double bond in a structure thereof such as unsaturated fatty acids and which is liable to cause a radical reaction, is used as a grinding aid, an antioxidant may be added during flaking in the first process. In addition, when a material is used which has an unsaturated double bond in a structure thereof as an organic compound having a polar group in the second process and which is liable to cause a radical reaction, an antioxidant may be added during the second process or after the second process is completed.

Any compound may be used as the antioxidant that is usable in the present disclosure, as long as the compound has a function of stopping a radical chain reaction by supplying electrons or hydrogen atoms to radicals generated by deterioration of the above-described unsaturated fatty acids. A representative antioxidant that may be used in the present disclosure includes a synthetic antioxidant and a natural antioxidant such as a phenol compound, an alicyclic compound having a carbonyl group and a hydroxyl group, an aromatic amino compound, an organic sulfur compound, and a phosphite compound.

In addition, as long as the first process and the second process are included, various other processes may be further included. For example, a solid-liquid separation process, such as a filtration operation or a screen operation, may be included.

Composition of aluminum flakes is the same as composition of raw material aluminum powder in a method of manufacturing the aluminum flake paste described above. That is, the composition of the aluminum flakes is not limited in particular and may be composed of only aluminum or may be composed of an aluminum-based alloy. Purity of aluminum is also not limited in particular, and in order to further increase gloss of a coating film and a printed matter containing an aluminum flake paste, it is preferable to use pure aluminum in general, and more preferably, pure aluminum having purity of 99.9 mass % or more.

The content of aluminum flakes in the aluminum flake paste is not limited in particular, and when the content for the aluminum flake paste is 50 mass % or more and 85 mass % or less, storage stability may be increased, and an effect may be obtained in which dispersibility of aluminum flakes in a coating material may be increased at the time of coating. In addition, it is more preferable that the content is 60 mass % or more and 75 mass % or less.

The aluminum flakes of the present disclosure contain aluminum flakes having a surface area of 250 μm²

The aluminum flake paste of the present disclosure may include another additive in a range in which the effects of the present disclosure are not reduced. The additive may adhere to surfaces of the aluminum flakes or may be contained in the aluminum flake paste.

Other additives may include, for example, an antioxidant and various compounds for providing water resistance, chemical resistance, and weather resistance, as described in the manufacturing method of the aluminum flake paste described above.

Those of ordinary skill in the art related to the present embodiments may understand that various changes in form and details can be made therein without departing from the scope of the characteristics described above. The disclosed methods should be considered in a descriptive sense only and not for purposes of limitation. The scope of the present disclosure is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present disclosure. 

1. A wrapper comprising: a pulp layer; and metal particles uniformly distributed inside the pulp layer, wherein the metal particles contain a metal flake paste.
 2. The wrapper of claim 1, wherein the metal flake paste is made of aluminum, steel, iron, copper or a metal alloy.
 3. The wrapper of claim 1, wherein the metal flake paste is made by a method including: a first process of flaking raw material aluminum powder in an organic solvent containing aromatic hydrocarbons as a main component to obtain aluminum flakes; and a second process of treating the aluminum flakes obtained in the first process with an organic compound having a polar group and forming a paste.
 4. The wrapper of claim 3, wherein the organic compound having the polar group is at least one selected from the group consisting of fatty acids, aliphatic amines, fatty acid amides, aliphatic alcohols, and esters composed of fatty acids and aliphatic alcohols.
 5. A cigarette comprising: a tobacco rod containing an aerosol generating material; at least one filter segment; and a wrapper that wraps at least one of the tobacco rod and the at least one filter segment, ein the wrapper comprises: a pulp layer; and at least one metal particle distributed inside the pulp layer, and wherein the metal particle contains a metal flake paste.
 6. The cigarette of claim 5, wherein the metal flake paste is made of aluminum, steel, iron, copper, or a metal alloy.
 7. The cigarette of claim 5, wherein an aerosol is generated from the tobacco rod by an electric-heating-type heater inserted into the cigarette.
 8. A method of manufacturing a metal flake paste, the method comprising: a first process of flaking raw material aluminum powder in an organic solvent containing aromatic hydrocarbons as a main component to obtain aluminum flakes; and a second process of treating the aluminum flakes obtained in the first process with an organic compound having a polar group and forming a paste.
 9. The method of claim 8, wherein the organic compound having the polar group is at least one selected from the group consisting of fatty acids, aliphatic amines, fatty acid amides, aliphatic alcohols, and esters composed of fatty acids and aliphatic alcohols. 